The AT4 is recoilless. Western military's do use rpg's. Guided AT weapons are usually heavy/require a power source (battery) and the rounds are very expensive. Guided AT weapons are generally used for long range heavy/modern armoured threats. Guided AT weapons use thermal signitures to lock onto their designated target, best used against modern amour with a great heat signature.
Recoilless weapons are used for short range engagements against lightly armoured vehicles/troops/fortifications. These RPG's cost a lot less and are much easier for infantry sections to carry and use on a battlefield fighting a low-tech insurgency war.
In SPMBT there are no bean counters so go ahead use your Javelin to take out that sniper hidden in a building
)